To begin with, RFI from licensed radio transmitters (TV, and radio stations for example) because of a defect is extremely rare. Most of the time the RFI from the transmitter is caused by from cheap consumer electronics products. Improperly shielded computers are much often to blame for RFI than TV's and radios.

Within a computer, there are many different frequencies within the HF and VHFbands that are possible culprits for interference. Computers also use square waves in their systems which may causeharmonics all over the place. Video cards updating the screen and monitors are also paticularly good at generating RFI. Monitors are especially bad with their poorly shield plastic case. Interestingly, the innocent keyboard also generates RFI with its microprocessor and keyboard cable that act together to form a fairly good loop antenna that sends the signal and harmonics all about.